1. Field of the Invention
The present invention relates to a hydraulic system for controlling a belt-driven conical-pulley transmission (CVT) of a motor vehicle having a variably adjustable transmission ratio. The hydraulic system includes a first valve unit to ensure a contact pressure of the belt-driven conical-pulley transmission, a second valve unit to control the transmission ratio of the belt-driven conical-pulley transmission, and a hydraulic energy source to supply the hydraulic system with hydraulic energy. The present invention also relates to a belt-driven conical-pulley transmission controlled thereby and to a motor vehicle equipped therewith.
2. Description of the Related Art
Belt-driven conical-pulley transmissions can have a continuously variable transmission ratio, in particular automatically effected transmission ratio variation.
Such continuously variable automatic transmissions include, for example, a startup unit, a reversing planetary gearbox as the forward/reverse drive unit, a hydraulic pump, a variable speed drive unit, an intermediate shaft, and a differential. The variable speed drive unit includes two pairs of conical disks and an encircling member. Each conical disk pair includes one conical disk that is movable in an axial direction. Between the pairs of conical disks runs the encircling element, for example a steel thrust belt, a tension chain, or a drive belt. Axially moving the movable conical disk changes the running radius of the encircling member, and thus the transmission ratio of the continuously variable automatic transmission.
Continuously variable automatic transmissions require a high level of contact pressure applied to the encircling member in order to be able to move the axially movable conical disks of the variable speed drive unit with the desired speed at all operating points, and also to transmit the torque with sufficient basic pressure with minimum wear.
An object of the present invention is to provide a hydraulic system for a belt-driven conical-pulley transmission and/or a belt-driven conical-pulley transmission that includes a hydraulic shift-by-wire control and that can replace mechanical actuation of the parking lock and the clutch selection.
The above-identified object is achieved with a hydraulic system in accordance with the present invention for controlling a belt-driven conical-pulley transmission of a motor vehicle having a variably adjustable transmission. The hydraulic system includes a first valve arrangement to ensure a desired belt contact pressure in the belt-driven conical-pulley transmission, a second valve arrangement to control the transmission ratio of the belt-driven conical-pulley transmission, a hydraulic energy source to supply the hydraulic system with hydraulic energy, and a third valve arrangement to control a forward and a reverse clutch. The forward clutch and the reverse clutch are parts of a power train of the motor vehicle, and can optionally be actuated by means of the third valve arrangement, wherein the motor vehicle moves forward when the forward clutch is actuated and the motor vehicle moves backward when the reverse clutch is actuated. A mechanical intervention by means of a gearshift lever operable by a driver of the motor vehicle, for example, is not necessary to engage the forward or reverse gear of the motor vehicle.
The above-identified object is also achieved with a hydraulic system in accordance with the present invention for controlling a belt-driven conical-pulley transmission of a motor vehicle having a variably adjustable transmission. The hydraulic system includes a first valve arrangement to ensure a desired belt contact pressure in the belt-driven conical-pulley transmission, a second valve arrangement to control the transmission ratio of the belt-driven conical-pulley transmission, a hydraulic energy source to supply the hydraulic system with hydraulic energy, by providing a parking lock-release system to control a parking lock. The parking lock is normally produced by a mechanical intervention of an appropriate component, for example a pawl, in the power train of the motor vehicle. Advantageously, the mechanical lock can be actuated, i.e., engaged or released again, for example, by means of the parking lock-release system. A mechanical intervention that would require comparatively high manual force from a driver of the motor vehicle to operate the parking lock is not necessary.
A preferred exemplary embodiment of the hydraulic system is characterized in that the third valve arrangement includes a first valve having a first control piston for hydraulic actuation of the forward and reverse clutches. By means of the first control piston, the forward and the reverse clutch can optionally be supplied with hydraulic energy to engage or disengage them, or can be cut off from the hydraulic energy source.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the hydraulic parking-lock-release system includes a second valve for hydraulic actuation of a parking lock cylinder positioned downstream from the second valve, for mechanical control of the parking lock. The parking lock cylinder can be connected mechanically to the power train of the motor vehicle. To that end, a lever connected to a transmission shaft can be engaged with a corresponding recess of the parking lock cylinder, for example.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the third valve arrangement includes a third valve positioned upstream from the first valve to actuate the first control piston of the first valve. The third valve can be a control valve, for example an electrically actuatable proportional valve. By means of the actuation by the third valve, the forward or the reverse gear of the motor vehicle can optionally be engaged by selective actuation of the forward or reverse clutch.
Other preferred exemplary embodiments of the hydraulic system are characterized in that by means of the first control piston of the first valve
are optionally alternatively actuatable.
The forward and reverse clutches can be clutches that are disengaged when unpressurized. However, it is also conceivable to design the reverse and forward clutches so that they are engaged when unpressurized. Accordingly, in the second selector position the control piston can be switched so that both clutches are under pressure. When the forward and reverse clutches are designed as clutches that are disengaged when unpressurized, the result is a safety benefit, since in the event of a possible occurrence of a pressure loss of the hydraulic energy source, the neutral position results without further action, i.e., unpressurized forward and reverse clutches, wherein the vehicle can continue to move in free wheeling.
Another preferred exemplary embodiment of the hydraulic system is characterized in that a sensor system is provided to detect the first through third selector positions (R, N, D) of the first control piston. Advantageously, by means of the sensor system the actual shift states of the first control piston can be recognized and transmitted for further processing. The data thus obtained can be used for a display of the selector position actually chosen, for example. From the aspect of safety, it is possible to use the data obtained to recognize possibly unwanted intermediate conditions, or an unwanted selector position. For example, if an unwanted selector position results, that can be utilized to initiate an emergency function, for example emergency shutoff.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the sensor system includes a Hall-effect sensor to detect a position of the first control piston. The Hall-effect sensor can be employed as an additional safety device, and it can operate together with a corresponding magnet attached to the first control piston, for example. The Hall-effect sensor, as an additional part of the sensor system, can generate other safety-relevant information.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the first valve is connected upstream to the hydraulic energy source through a fifth valve. The supply of hydraulic energy to the first valve can be controlled by means of the fifth valve.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the first valve is connected downstream to a sixth valve to actuate the fifth valve. The fifth valve can be actuated by means of the sixth valve, which can be designed as a control valve, for example as an electrically actuatable proportional valve. It is conceivable to design the fifth valve so that when actuated accordingly it completely separates the first valve from the hydraulic energy source by means of the sixth valve, and at the same time switches the first valve to tank. That can be used advantageously as an emergency shutoff, where the reverse clutch and the forward clutch can be switched to zero pressure and therefore disengage, with the belt-driven conical-pulley transmission being shifted automatically to the neutral position. As an additional safety provision, it is conceivable to design the first control piston of the first valve so that in the unpressurized state, i.e., without control pressure from the third valve, it moves automatically into a selector position in which the forward and reverse clutches are switched to zero pressure.
Another preferred exemplary embodiment of the hydraulic system is characterized in that to actuate the second valve the second control piston is connected to the hydraulic energy source through the fifth valve. The fifth valve can serve to control the second valve, whereupon a connection to the hydraulic energy source can bring about a release of the parking lock. Advantageously, the fifth valve is also connected ahead of the first valve for clutch actuation. Advantageously, raising the pressure for the first valve to engage one of the clutches also acts through the second valve to bring about a release of the parking lock. That advantageously ensures that when the clutch is engaged or as the clutch is engaging, the parking lock is released.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the second valve includes hydraulic self-retention. The parking lock can be released by means of the hydraulic latching feature, even when the control pressure is dropping. That advantageously ensures that the hydraulic parking lock remains unlocked as long as the hydraulic energy source is also supplying hydraulic energy, for example in the case of a mechanically driven pump, i.e., one that is connected to the internal combustion engine of the motor vehicle.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the second valve arrangement includes a seventh valve to adjust the transmission ratio. Corresponding adjusting elements of the belt-driven conical-pulley transmission can be controlled by means of the second valve arrangement to adjust the transmission ratio.
Another preferred embodiment of the hydraulic system is characterized in that a first flow chamber and a second flow chamber of the seventh valve are selectively variably connected to set the transmission ratio and to the hydraulic energy source or to the tank. The requisite pressure to set the transmission ratio can be applied to the adjusting elements via the first and second flow chambers.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the first and the second flow chambers are connected to the second valve downstream through an OR element to achieve the hydraulic self-retention. A corresponding pressure surface of the second control piston can advantageously be subjected to pressure through the OR element, it being sufficient that one of the two flow chambers is pressurized.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the first and the second flow chambers are connected downstream through the OR element and the second valve in the parking-lock release cylinder. By means of the latching feature and the OR element, the parking-lock release cylinder can be pressurized so that the parking lock can be released. The pressure to release the parking lock is provided by the first or second flow chamber of the seventh valve.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the first and second flow chambers of the seventh valve are connected to the tank through a ninth valve to raise the tank pressure. An increase in tank pressure can be achieved by means of the ninth valve.
Another preferred exemplary embodiment of the hydraulic system is characterized in that a ninth control piston of the ninth valve is actuatable through a fourth valve. The fourth valve can be a control valve, for example an electrically actuatable proportional valve.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the ninth valve arrangement includes control stages to control the increase in tank pressure. The magnitude of the increase in tank pressure can advantageously be set by means of the control stages.
Another preferred exemplary embodiment of the hydraulic system is characterized in that a tenth valve with a tenth control piston is connected downstream from the hydraulic energy source for prioritized supplying of the hydraulic system with hydraulic energy. The tenth valve can supply the downstream components of the hydraulic system with hydraulic energy in accordance with a desired priority.
Another preferred exemplary embodiment of the hydraulic system is characterized in that with a first, small amount of energy only the first valve arrangement is supplied by means of the hydraulic energy source, and with a second, larger amount of energy additional components of the hydraulic system are also supplied. Advantageously, that makes it possible to ensure that when the internal combustion engine of the motor vehicle is started the necessary contact pressure in the transmission can be supplied first.
Another preferred exemplary embodiment of the hydraulic system is characterized in that with a third amount of energy, greater than the second amount, the components of the hydraulic system are supplied with limited hydraulic energy. To that end the tenth valve can divert surplus hydraulic medium directly into the tank circuit, to thereby prevent the pressures in the remainder of the downstream system from getting too high when the hydraulic energy source is rotating rapidly, i.e., when large volumetric flows are being transported.
Another preferred exemplary embodiment of the hydraulic system is characterized in that a fourth valve arrangement is provided to control a volumetric flow of cooling oil, in particular to cool the clutches. Components of the power train, for example the forward and reverse clutches, a centrifugal oil cover, and/or conical disks, as well as encircling elements of the belt-driven conical-pulley transmission, can advantageously be subjected to a controlled volumetric flow of cooling oil by means of the fourth valve arrangement.
Another preferred exemplary embodiment of the hydraulic system is characterized in that the fourth valve arrangement includes the fourth valve for actuation. The fourth valve can thus simultaneously actuate the ninth control piston of the ninth valve and the fourth valve arrangement. Advantageously, the fourth valve can be so designed as a proportional valve. It is conceivable to design the fourth valve as a proportional valve, in which case the valves connected downstream are actuatable by just one valve. To that end the control surfaces and return springs of the actuated valves can be designed accordingly and can respond in various ranges, for example.
The object is also achieved with a belt-driven conical-pulley transmission having a hydraulic system of the type described above.
The object is also achieved with a motor vehicle having a belt-driven conical-pulley transmission and a hydraulic system of the type described above.
The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying drawings, in which:
Connected downstream from hydraulic energy source 7 is a first valve arrangement 9, which is connected to a torque sensor 11. First valve arrangement 1 and torque sensor 11 serve to provide and/or control a contact pressure for transmitting torque between conical disk pairs and a corresponding encircling element of belt-driven conical-pulley transmission 3, in particular as a function of the torque present at the input side of the belt-driven conical-pulley transmission 3. Downstream, torque sensor 11 is connected to a cooler return 31 through a cooler (not shown). Torque sensor 11 can raise or lower a system pressure 45 delivered by the hydraulic energy source, as a function of the torque that is present.
A second valve arrangement 13 is also connected downstream from hydraulic energy source 7. Second valve arrangement 13 is connected to conical disk pairs indicated generally by reference numeral 15, and serves to adjust the positions of the conical disks 15, i.e., to set the transmission ratio of belt-driven conical-pulley transmission 3.
Also connected downstream from hydraulic energy source 7 is a third valve arrangement 17, which is connected to actuate a forward clutch 19 and a reverse clutch 21, and which are only generally indicated by their respective reference numerals.
A hydraulic parking-lock release system 23 is also connected downstream from hydraulic energy source 7. The parking-lock release system 23 of hydraulic system 1 is connected to a mechanical parking lock 25 indicated generally by reference numeral 25. The connection can be effected by means of suitable mechanical aids, for example a lever. By means of the parking-lock release system 23, the mechanical parking lock 25 of motor vehicle 5 can be engaged, i.e., established, and released again.
Hydraulic energy source 7 also serves to supply a fourth valve arrangement 27. Fourth valve arrangement 27 serves to provide a volumetric flow of cooling oil that is likewise provided by means of hydraulic energy source 7. To that end, fourth valve arrangement 27 is connected to a cooling circuit generally indicated by reference numeral 29, in particular to the cooler return 31, to an active Hytronic cooling system 33, to a jet pump 35, and to a centrifugal oil cover 37, each of which is only generally indicated by its respective reference numeral.
Hydraulic energy source 7 is connected downstream through a branch 39 to a pilot-pressure regulating valve 41. Pilot-pressure regulating valve 41 regulates a downstream pilot pressure 43, for example of around 5 bar, while the hydraulic energy source 7 provides a higher system pressure 45. The pilot pressure serves in a known way by means of suitable proportional valves, for example electrically actuatable proportional valves, to control the circuit components of hydraulic system 1.
To adjust and distribute the hydraulic energy supplied by hydraulic energy source 7, a fifth valve arrangement 47 is provided. Fifth valve arrangement 47 ensures priority supply to the torque sensor 11 and to the second valve arrangement 13, for example when starting the engine of the motor vehicle 5. In addition, it conducts the excess volumetric flow of the hydraulic energy source directly in the direction of the cooler return 31.
To set or regulate the system pressure 45 upstream of torque sensor 11, the latter includes pressure regulating valves (not shown). First valve arrangement 9 includes a system pressure valve 49 connected upstream of torque sensor 11. System pressure valve 49 is connected downstream from fifth valve arrangement 47, and allows passage of an appropriate volumetric flow for torque sensor 11, while the system pressure 45 downstream can be adjusted to a minimum system pressure, for example 6 bar. To set the adjusting pressure through short-term additional elevation of the system pressure 45, system pressure valve 49 is additionally connected upstream to second valve arrangement 13 through an OR element 63.
Second valve arrangement 13 includes a seventh valve 51 having a seventh control piston 53 and connected downstream from hydraulic energy source 7. Seventh control piston 53 is connected upstream to an eighth valve 55 for actuation. The eighth valve 55 can be a control valve, for example an electrically actuatable proportional valve. Seventh valve 51 includes a first flow chamber 57 and a second flow chamber 59, which are each connected to corresponding adjusting elements of the conical disks 15. By means of the seventh control piston 53 of the seventh valve 51, hydraulic energy source 7 can optionally be connected continuously, i.e., with transfer flow, to first flow chamber 57 or to second flow chamber 59. The particular flow chamber that is not connected to the hydraulic energy source 7 can accordingly be connected to a tank 61. In a middle position, both flow chambers 57 and 59 can be disconnected from the hydraulic energy source 7 and switched to the tank 61. Thus a desired pressure ratio can be set in flow chambers 57 and 59 by means of the seventh valve 51 of second valve arrangement 13 to adjust the conical disks 15. In addition, flow chambers 57 and 59 are connected to system pressure valve 49 through the OR element 63 upstream of the latter. Through that connection, the minimum system pressure, adjusted by means of system pressure valve 49, can be adjusted by a desired amount to the seventh valve 51, i.e., for example raised, by means of adjusting motions made by means of the latter.
Fourth valve arrangement 27 includes a cooling oil regulating valve 67 that is actuated by means of a fourth valve 65. Cooling oil regulating valve 67 is connected downstream from the fifth valve arrangement 47, and is supplied thereby with hydraulic energy by means of hydraulic energy source 7. In addition, fourth valve arrangement 27 includes a return valve 69, which is connected upstream directly to hydraulic energy source 7 or to a pump injector 70 of hydraulic energy source 7. Return valve 69 is connected downstream with a through connection to centrifugal oil cover 37 through a flow chamber of return valve 69, and as the volumetric flow rises it conveys a partial flow directly into the pump injector 70. Cooling oil regulating valve 67 serves to maintain and regulate a desired cooling oil volumetric flow through jet pump 35 to the components to be cooled, forward clutch 19 and reverse clutch 21.
The third valve arrangement 17 includes a first valve 71 having a first control piston 73. To actuate the first control piston 73, the latter is connected downstream to a third valve 75, for example a control valve such as an electrically actuatable proportional valve. The first control piston 73 of the first valve 71 can assume essentially three selector positions to actuate the forward clutch 19 and the reverse clutch 21. In a first selector position, which is shown in
In a second selector position, which corresponds to a displacement of the first control piston 73 of first valve 71 to the right, as viewed in the orientation shown in
In a third selector position, which corresponds to a further displacement of first control piston 71 to the right, as viewed in the orientation shown in
The parking-lock release system 23 includes a parking lock cylinder 85. Parking lock cylinder 85 can be biased toward the left, as viewed in the orientation shown in
The second valve 89 includes a second control piston 91. The second control piston 91 includes a hydraulic latching feature 93. Using the hydraulic latching feature, a pressure that is present at the end face 87 of the parking lock cylinder 85 is recirculated to a second pressure surface of the second control piston 91, the latter being held in its open position by that recycling, in particular in the event that there is no longer a control pressure present at the second control piston 91 through the fifth valve 79. The pressure is then supplied, with the second control piston 91 moved to the right as viewed in the orientation shown in
Ninth valve 95 includes a ninth stepped control piston 97. Flow chambers 57 and 59 can be connected to tank 61 with a variable pressure drop via the steps of the stepped ninth control piston 97, so that a minimum pressure, for example 6 bar, exists in flow chambers 57 and 59, even at the zero crossing. For actuation, the ninth valve 95 is connected to the fourth valve 65, which also actuates cooling oil regulating valve 67. Cooling oil regulating valve 67 and ninth valve 95 are thus equally actuated by fourth valve 65. In principle, it is conceivable to design the control surfaces and/or directions of action of valves 67 and 95 differently. Valves 67 and 95 can be designed with different response thresholds, so that in a first response range, for example, a tank pressure increase results when the cooling is on, in a second response range there is no tank pressure increase but there is cooling, and in a third response range there is no tank pressure increase and no cooling occurs.
For prioritized supply of valve arrangements 9, 13 and of torque sensor 11 before valve arrangements 17, 27, hydraulic system 1 includes a tenth valve 99 having a tenth control piston 101. Tenth valve 99 operates together with an orifice plate B1, an orifice plate B2, a check valve 103, and a pressure relief valve 104. Orifice plate B1 allows a greater volumetric flow, for example 15 l/min, than orifice plate B2, for example 3 l/min. When the volumetric flow is comparatively low, torque sensor 11 is supplied with hydraulic energy through orifice plate B2. In addition, second valve arrangement 13 is likewise supplied with hydraulic energy with first priority by way of a branch 105. As the delivery volume increases, tenth control piston 101 moves to the left, as viewed in the orientation shown in
To detect the position of parking pawl 123, a position sensor 127 can be provided, which interacts by means of magnets 129, for example, that are operatively associated with the selector shaft 119. The selector position of the parking pawl 123 can be determined by means of the position sensor 127 and the magnets 129.
In a second selector position of tenth valve 99, shown in the center of
As shown to the right in
It is possible by means of the hydraulic system shown in
Fourth valve 65 is connected upstream of cooling oil regulating valve 67 and ninth valve 95.
Parking lock cylinder 85 operates against an externally applied parking pawl 123 and engagement spring 125, which urges the parking lock cylinder 85 back into its initial position at the zero pressure position. Advantageously, a comparatively large force can be achieved by applying the comparatively high system pressure 45, resulting in reliable disengagement of the parking lock 25.
Advantageously, in the event of an electric power failure both clutches can be switched to zero pressure automatically by means of fifth valve 79, while at the same time parking lock 25 can be released hydraulically, since in that case second valve 89 also automatically switches parking lock cylinder 85 to the tank 61 so that the motor vehicle 5 is secured against unintended rolling away.
As an additional safety monitoring element, first control piston 73 includes sensor 199, for example a Hall-effect sensor. The sensor 199 shown in
Hydraulic system 1 in accordance with the invention provides the following functions for the hydraulic control: hydraulic actuation and selection of the forward and reverse clutch, cooling the clutch, moving the pulleys of the CVT transmission, biasing the pulleys of the CVT transmission, providing a volumetric flow of oil through the cooler, and actuation (releasing) of the parking lock. Advantageously, it is possible to replace a previously employed “manual” selector (clutch selection) with a pilot-operated selector. At the same time, a parking-lock release system can be added. Advantageously, comparatively few solenoids and selector valves are needed, enabling savings in both construction space and cost aspects.
In summary, the following are included: a modified clutch actuating system and the actuation of the parking-lock release system 111 or parking lock 25, the prioritizing tenth valve 99, and the ninth valve 95. Advantageously, that enables the control to cover other supplemental functions. Those include prioritized supplying of oil to the torque sensor 11 before supplying the clutch, and an additional biasing function of the pulleys by raising the tank pressure for the seventh valve 51. For reasons of safety, hydraulic self-retention of the parking lock 25 (with the engine running) is achieved.
Parking lock cylinder 85 operates selector shaft 119 or a parking lock linkage, and is actuated by second valve 89. The resetting is accomplished by the engagement spring 125 acting on the selector shaft 119.
The first valve 71 selects the clutches 19, 21: R (reverse clutch 21 filled), N (both clutches 19, 21 bled), D (forward clutch 19 filled).
The third valve 75 controls the pilot pressure of the first valve 71.
The ninth valve 95 raises the pressure level of the tank return of the seventh valve 51, and is also actuated through the fourth valve 65.
The second valve 89 controls the parking lock cylinder 85, and thus releases the parking lock 25. It contains a hydraulic self-retainer 93. The working pressure is supplied through an OR element 63 from the first or second flow chamber 57, 59 (SS1_adjust or SS2_adjust).
The tenth valve 99 primarily regulates the volumetric flow through the torque sensor circuit 11 (MF circuit). At the same time, at the beginning of the engine startup it sets the volumetric flow so that the torque sensor circuit 11 always includes a minimum volumetric flow available before all other components are supplied.
Actuation of the parking lock 25 is assumed by the second valve 89. When the clutch pressure exceeds a threshold value, disk set SS1 or SS2 adjusting pressure is applied to the piston working surface of the parking lock cylinder 85—the parking lock 25 is disengaged. Second valve 89 goes to self-retention 93.
Ninth valve 95 takes over increasing the tank pressure. It is actuated through fourth valve 65 (cooling pressure regulator). A “stepped” ninth control piston 97 can be used to vary the pressure level above the pilot pressure (pressure return).
The increase in tank pressure causes a uniform increase in the contact pressure of the disk sets, in addition to the set contact pressure of the system pressure valve 49.
That can be employed to capture peaks of torque in critical driving maneuvers (such as ABS deployment).
At the same time, it is also employed to hold the pressure level at a minimum of approximately 6 bar (the holding pressure of the parking lock cylinder 85) during zero crossing of the seventh valve 51. Thus, it provides the hydraulic self-retention 93 of the second valve 89 and of the downstream parking lock cylinder 85.
That enables the parking lock 25 to be kept disengaged even if the power fails while traveling (until the pump 7 comes to a stop=engine off).
The parking lock can be engaged by the engagement spring 125 if:
1. no clutch pressure is applied,
2. the seventh valve 51 is in the middle position (no adjusting pressure), and
3. the ninth valve 95 is in the “no tank pressure increase” position.
That cancels the self-retention, and the second control piston 91 bleeds the parking lock cylinder 85.
The parking lock cylinder 85 is then urged into the “parking lock engaged” position by the engagement spring.
The prioritizing tenth valve 99 supplies the torque sensor 11 with a minimum volumetric flow Q_MFmin (adjustable by means of orifice plate B2) before all other components.
If the set volumetric flow is exceeded, the pressure drop through orifice plate B2 pushes the slide open far enough against the spring until the control edge is at the second flow chamber of the valve.
Then the fifth valve 79 and all other components are also supplied with oil. Almost all the oil flows through the check valve 103 and the orifice plate B1. If the volumetric flow reaches a set limit, the tenth control piston 101 is pushed by the pressure drop at orifice plate B1 into a corresponding limiting-regulating position, at which the surplus volumetric flow is returned to the pump and thus no longer flows through the torque sensor circuit (the tenth valve 99 regulates the total volumetric flow).
The interconnection in the illustrated hydraulic circuit ensures the following safety functions: In the event of a power failure, both clutches are switched automatically to zero pressure; only when the engine is stopped is the parking lock 25 “hydraulically” released (engagement position), since the second valve 89 is able to get out of self-retention 93. (Vehicle 5 is secured against “rolling away” when stopped; while driving, the parking lock 25 cannot catch when the engine is running).
As an additional safety control, a travel/position sensing system 127, 129 is applied to the selector shaft 119 based on the existing sensors. The sensors report to the control device the position and the direction of motion of the selector shaft 119 or of the parking lock slide or cylinder 85.
As additional safety monitoring, a slide travel sensor system 197 based on a Hall-effect sensor 199 is applied to the first control piston 73 (see
Although particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. It is therefore intended to encompass within the appended claims all such changes and modifications that fall within the scope of the present invention.
Number | Date | Country | |
---|---|---|---|
60902561 | Feb 2007 | US | |
60902562 | Feb 2007 | US | |
60902563 | Feb 2007 | US | |
60919398 | Mar 2007 | US | |
60937273 | Jun 2007 | US | |
60937274 | Jun 2007 | US | |
60937275 | Jun 2007 | US | |
60937276 | Jun 2007 | US |